Non-invasive brain-to-brain interface: links between two brains

Direct communication between the brains of human and rat .... or between humans
April 8, 2013

Block diagram of brain-to-brain interface (BBI). Left: steady-state visual evoked potential (SSVEP)-based brain-to-computer interface; right:focused ultrasound-based computer-to-brain interface (CBI). (Credit: Yoo S-S et al./PLoS ONE)

We reported last month how Duke University researchers remotely linked the brains of two rats. Now researchers from the U.S and South Korea have have taken it a step further: a non-invasive functional link between the brains of different species (human and rat) — a brain-to-brain interface (BBI).

Researchers at Brigham and Women’s Hospital and Harvard Medical School set up a system intended to allow a human to remotely make a rat’s tail flick. There were to be no direct connections between human and rat, and no direct connections to their brains (such as implantable cortical microelectrode arrays, like those used in the Duke research and in BCI systems for quadriplegic patients, such as BrainGate).

The BBI system had two parts: a BCI, using EEG sensors and computer to pick up intention from the human; and transcranial sonication of focused ultrasound (FUS) to modulate the neural activity of specific brain regions in the rat’s brain.

Wagging the rat

Here’s how it worked:

1. Human volunteers looked at a strobe image (flickering) and EEG sensors picked up the resulting  visual evoked potentials synchronized with the light.

2. The acquired EEG signal was filtered through a digital bandpass filter centered at the flickering frequency (to eliminate other brain signals). A computer analyzed the resulting signals, determined statistically when there was a significant detection, and sent a signal to the rat.

3. A piezoelectric ultrasound transducer operating at 350 kHz delivered focused acoustic pressure waves on the motor area of an anesthetized rat’s brain associated with tail movement.

4. The rat’s tail movement was detected by a motion sensor.

The “Brainstorm’ scenario


Brainstorm (credit: MGM)

This experiment was limited to a simple on-off signal. However, the researchers say it should be possible to detect hand movements by using multiple EEG signals or real-time fMRI.

Those signals (on multiple channels) could be used to “sonicate each of the corresponding hemispheric forepaw motor areas of the rat’s brain, resulting in mirror-like limb-to-limb control of the rodent forepaw motion.”

But the research could go a lot further, in a concept right out of the movies The Cell (an FBI agent persuades a social worker to enter the mind of a comatose serial killer to learn where he has hidden his latest kidnap victim) and Brainstorm (a team of scientists invents “the Hat,”a brain/computer interface that allows sensations to be recorded from a person’s brain so that others can experience them). The researchers suggest this could happen between two awake human subjects. And it could be bidirectional, and over great distances, using the Internet.

What’s more, “Potential linking/sharing of neural processing information between individual identities can be conceptually applied to a feedback loop of the neural signal, enabling ‘autologous BBI’”— that is, the information would be fed back to the originating person. So it could be used to actively control or modify specific neural processing and associated cognitive/neural behavior, “which may confer unexplored opportunities in the study of neuroscience with potential implications for therapeutic applications.”

The findings suggest “intriguing new possibilities for computer-assisted volitional control/communication of brain states between individuals,” the researchers hint. “The BBI method may be used to augment this mutual coupling of the brains, and may have a positive impact on human social behavior” — or negative, if misused.

This technology raises some ethical questions, the researchers admit, and “complex challenges, possibly even undesirable consequences that may arise with the future application of this emerging technology.”